1. Field of the Invention
The present invention relates to a slot machine, and more particularly to a slot machine in which a plurality of reels are arranged in a matrix.
2. Description of the Related Art
In a conventional slot machine, a plurality of reels, for example, three to five reels are disposed in a horizontal row. These reels are rotated at the same time, upon actuation of a start lever. The reels are thereafter stopped sequentially at random timings. In a manual stop type, a stop button is provided for each reel and upon actuation of a stop button the corresponding reel stops. Various symbols such as "7", "apple", "banana", "star" and "bell" are displayed on the outer circumference frame of each reel.
In a conventional slot machine, an observation window is provided for each reel, and three symbols are fully visible through each observation window. Three horizontal winning lines are thus formed, each winning line including three symbols in the upper, middle or lower areas of the observation windows. Two additional winning lines are also formed diagonally by three symbols in the case of three windows. A conventional slot machine has therefore a maximum of five winning lines in all. The number of valid winning lines increases up to this maximum as the number of coins (including tokens) inserted into a coin inlet prior to the start of a game increases. For example, one horizontal winning line is made valid if one coin is inserted, three horizontal winning lines are made valid if two coins are inserted, and all five winning lines are made valid if three coins are inserted.
A slot machine which is operable with a pre-paid card has recently been proposed. With a slot machine of this type, a credit button is operated prior to starting a game, and the number of coins to be bet is determined by the number of times the credit button is pushed.
When all the reels stop, and if any combination of a plurality of symbols on a valid winning line is a winning symbol combination, a predetermined number of coins corresponding to the rank of the winning symbol combination are paid out. Alternatively, instead of paying out actual coins, a credit counter is actuated in some slot machines.
In order to increase a player's enjoyment of the game, a plurality of bonus games can be awarded to the player if all the symbols on a particular winning line are "7". The nature of a bonus game can change with the type of slot machine. For example, in some slot machines, when one coin is entered, only one reel rotates. If a particular symbol appears when the reel stops, a win or hit is given. In such a bonus game, the reels are controlled to stop so as to make a particular winning symbol appear with a high probability.
Conventional slot machines such as described above have only five winning lines, thus providing relatively few chances to win. Furthermore, if the first stopped reel does not show the symbol "7", the player knows at this time that there is no longer any chance of winning a bonus game which the player has most desired; so the player loses interest in the game even though the remaining reels are still rotating.